Besides CCDs (charge-coupled devices), image sensing devices based on CMOS technology constitute a widespread variant of image sensors. Sensors based on CMOS technology have the advantage over CCDs that electronic circuits can be co-integrated very simply on a chip, which makes complex system-on-chip solutions possible.
DE 10 2006 030 541 A1 describes an arrangement in which electromagnetic radiation-emitting elements and electromagnetic radiation-detecting elements are located together on a chip. In this case, the two element types may be arranged in a matrix on the chip. A disadvantagous effect of this is that the immediately adjacent arrangement of electromagnetic radiation-emitting elements and electromagnetic radiation-detecting elements leads to cross-coupling.
WO 2012/163312 A1 discloses bidirectional displays on which a plurality of light-generating image elements and a plurality of light-detecting elements are arranged in the form of an array. In this case, the light-generating image elements as a whole may, for example, function as a display surface of a display and the light-detecting elements as a whole may, for example, function as a sensor of a camera. WO 2012/163312 A1 furthermore describes different driving variants for the elements, which are intended to solve the problem of direct crosstalk from light-generating image elements to adjacent light-detecting elements by driving the light-generating image elements and adjacent light-detecting elements successively. Light-generating image elements and adjacent light-detecting elements are therefore actively effective only alternately in succession.
When a light-detecting element is activated, a single full exposure phase is always followed by a readout phase of this light-detecting element. All the light-detecting elements are driven in the same way. In relation to the light-detecting elements as a whole, and therefore the function as a camera, only the functionality of the shutter of the camera is varied. Driving for both a global shutter and for a rolling shutter is described.
When the light-generating image elements of a bidirectional device function as a display, the driving variants disclosed in WO 2012/163312 A1 reach their limitations. In particular, the inactivity of the light-generating image elements during an exposure time of light-detecting elements, which requires a particular length for a good signal quality, may lead to perceptible image perturbations, or at least to a visible brightness loss. The sensitivity of the detector elements in turn cannot be increased arbitrarily since ever-higher resolutions are required in display applications, while the chip area used should remain as small as possible for cost reasons, so that the space for detector elements or circuit-technology measures to increase the sensitivity thereof are thus greatly restricted.